Investment Securities (Disclosure Regarding Length of Time on Investment Securities with Temporary Impairment) (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	$ 13,659	$ 14,530
Less than 12 months, gross unrealized losses	(142)	(57)
12 months or longer, fair value	407	2,093
12 months or longer, gross unrealized losses	(18)	(73)
Total, fair value	14,066	16,623
Total, gross unrealized losses	(160)	(130)
Agency Obligations
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value		3,601
Less than 12 months, gross unrealized losses		(9)
12 months or longer, fair value		0
12 months or longer, gross unrealized losses		0
Total, fair value		3,601
Total, gross unrealized losses	0	(9)
State And Municipal Obligations
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	10,143	7,675
Less than 12 months, gross unrealized losses	(103)	(42)
12 months or longer, fair value	407	2,093
12 months or longer, gross unrealized losses	(18)	(73)
Total, fair value	10,550	9,768
Total, gross unrealized losses	(121)	(115)
Corporate Obligations
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	3,516	3,254
Less than 12 months, gross unrealized losses	(39)	(6)
12 months or longer, fair value	0	0
12 months or longer, gross unrealized losses	0	0
Total, fair value	3,516	3,254
Total, gross unrealized losses	$ (39)	$ (6)